This application for a Mentored-Patient Oriented Research Career Development Award is designed to prepare the candidate for a career in clinical research in drug use disorders with a special emphasis on marijuana use, abuse, and dependence. The training plan involves course work, supervised readings, and "hands on" experience with leading experts in the pharmacology of cannabinoids and the treatment of marijuana dependence. There is a disconnect between the advances in the pharmacology and basic science of cannabinoids and clinical research in this area. By studying both basic science and clinical aspects, the candidate will be well-positioned to design and carry out methodologically sound patient-oriented research with a strong theoretical background. Developing this well-rounded perspective and expertise in the area of cannabinoids and marijuana abuse and dependence is the aim of the training plan outlined. The proposed research project integrates the candidate's experience in conducting pharmacotherapeutic trials with newly developed skills in motivational interviewing. The clinical research that has been conducted in the area of marijuana use and dependence has almost exclusively focused on psychotherapeutic interventions, including motivational interviewing. However, recent neuroscientific advances, such as the discovery of the cannabinoid receptors, suggest that pharmacotherapeutic strategies for treating marijuana dependence should be explored in conjunction with psychotherapeutic interventions. As anxiety may play a key role in marijuana abuse anxiolytic medications in particular may prove useful in reducing marijuana use. The hypothesis to be tested in the proposed research project is whether buspirone, an anxiolytic medication, will increase efficacy in reducing marijuana use in marijuana-dependent patients when delivered with motivational interviewing. The study will be a 12-week, randomized, double-blind, placebo-controlled trial evaluating a flexible dose of buspirone or placebo in combination with motivational interviewing. The primary outcome measure will be marijuana use as assessed by self-report and weekly urine drug screens. The results of this study will help guide future directions for research in the area of marijuana dependence.